Transition-Metal-Catalyzed Tandem C-H Functionalization/Annulation Reactions Via Redox-Neutral Pathways

The transition-metal-catalyzed C-H functionalization reactions have been proved to be effective methods for the construction of C-C bonds and C-X bonds(X = heteroatoms).Owing to their atom and step economy characters,the development of transition-metal-catalyzed C-H functionalization methodology has become one of the hot research fields in organic synthesis.This thesis mainly studied the transition-metal-catalyzed tandem C-H functionalization/annulation reactions under redox-neutral reaction conditions,including Rh(?)-catalyzed tandem C-H functionalization/spirocyclization of quinoxalinones with internal alkynes to synthesize spiroquinoxalinone derivatives,and Co(?)-catalyzed synthesis of isoquinolinone derivatives via annulative vinylene transfer using vinylene carbonate as C2 synthon.The dissertation is composed of three aspects as following:1)The research progress of transition-metal-catalyzed tandem C-H functionalization/annulation reactions for the synthesis of spirocycles and heterocycles were reviewed in detail,involving oxidative and redox-neutral tandem C-H functionalization/annulation reactions utilizing olefins,alkynes,alkenes et al as the substrates.2)The Rh(?)-catalyzed imine-directed sequential C-H functionalization/spirocyclization reaction was found for the synthesis of spiroquinoxalinones.A series of complex quinoxalinone derivatives were effectively synthesized under redox-neutral reaction conditions.The mechanistic studies implied that Piv OH acted as a proton shuttle in the catalytic cycle thus benefited the overall yield.3)The Co(?)-catalyzed redox-neutral synthesis of isoquinolinones employing vinylene carbonate as the C2 synthon via vinylene transfer has been developed.The reaction utilizing ?-oxygen elimination to promote the catalytic cycle displayed good functional group tolerance and regioselectivity,affording the corresponding products with good to excellent yields.By using the Co(?)-catalyzed vinylene transfer reaction and intramolecular Heck reaction as the two step,sequential ring closure strategy,three-step total synthesis of 8-oxopseudopalmatine and oxopalmatine were realized.In the thesis,transition-metal-catalyzed sequential C-H functionalization/annulation reactions for the synthesis of spirocycles and heterocycles via redox neutral pathways was proposed and realized,providing effective and practical accesses to spiroquinoxalinones and isoquinolinones.